Diesel exhausts do cause cancer, says WHO
Wednesday, 13 June 2012 at 1:56:PM
Diesel exhaust has been officially recognised to cause cancer, according to a group working for the World Health Organisation (WHO), and today reported by the BBC.
Diesel exhaust was last examined by the International Agency for Research on Cancer (IARC) in 1988, when it was placed in the ‘probably carcinogenic to humans’ category (Group 2A). The latest assessment as ‘carcinogenic to humans’ (Group 1) follows a thorough review of the available evidence, which included a large study of mine workers in the US.
The IARC report found ‘sufficient evidence’ that diesel exhaust is a cause of lung cancer, and a ‘positive association’ with an increased risk of bladder cancer. These findings reinforce the long-held view that exposure to exhaust fumes can be harmful, with short-term and long-term effects.
Health effects from diesel fumes have several causes. The particulates themselves (known as diesel particulate matter or DPM), as they are less than a micron in size, would be hazardous just on their own. Adding to the mix are harmful gases such as sulfur dioxide, carbon monoxide, and nitrogen oxides. The latter in particular (along with a number of volatile organic compounds) can lead to the production of low-level ozone. However, it is the chemicals absorbed onto the particulates that pose both a health hazard and a challenge for the analyst.
Many of these chemicals result from high-temperature diesel combustion, with polycyclic aromatic hydrocarbons (PAHs) being of particular concern. PAHs are widely considered to be carcinogenic because of their interference in the transcription of DNA, and benzo[a]pyrene is the archetypal PAH in this respect. The big problem for those tasked with assessing exposure to these chemicals is that they can be difficult to detect and quantify. This is because of their structural similarity and because it is easy for them to become ‘lost’ in amongst the plethora of other chemicals present.
In such situations, analysts need instrumentation that is optimised to detect challenging analytes in complex matrices. Our Application Note TDTS 97 describes just such an example, explaining how thermal desorption and GC/MS can be used for the detection of PAHs such as phenanthrene and pyrene in diesel exhaust.
Nicola Watson, Environmental Applications Specialist at Markes, welcomes the IARC report. She says “Although street-level emissions from diesel exhaust are now greatly reduced in many regions, including the US and Europe, the potential for hazardous levels of exposure remains amongst industry workers and in countries with less stringent regulations. There thus remains a need for careful monitoring of diesel emissions, especially with regard to cancer-causing aromatic hydrocarbons, and Markes is keen to help industry analysts develop ever-better methods for achieving this”.
David Barden received his Ph.D. in Organic Chemistry from Cambridge University in 2004, and during his time as an editor at the RSC wrote news pieces for Chemistry World on various scientific topics. He is now Technical Copywriter at Markes International, where he draws on the expertise of his colleagues to explain how new thermal desorption and mass spectrometry technologies can be applied to analyse volatile organic compounds in a wide variety of situations.
For the above-mentioned review of lung cancer in mine workers, see: D.T. Silverman et al., The diesel exhaust in miners study: A nested case–control study of lung cancer and diesel exhaust, Journal of the National Cancer Institute, 2012 (http://dx.doi.org/10.1093/jnci/djs034).
For a review of the link between exposure to PAHs and lung cancer, see: B. Armstrong, E. Hutchinson, J. Unwin and T. Fletcher, Lung cancer risk after exposure to polycyclic aromatic hydrocarbons: A review and meta-analysis, Environmental Health Perspectives, 2004, 112: 970–978 (http://dx.crossref.org/10.1289%2Fehp.6895).
For a comprehensive overview of diesel, diesel engines, and issues of air quality, see: Diesel fuels technical review, Chevron Corporation, 2007 (http://www.chevronwithtechron.com/products/documents/Diesel_Fuel_Tech_Review.pdf)